Synthesis of phosphorane compounds

ABSTRACT

Synthesis of phosphorane compounds by reaction of a triarylphosphine, an Alpha -haloester and an amine.

United States Patent Roberts et a]. [4 1 Aug. 1, 1972 [54] SYNTHESIS OF PHOSPHORANE 3,097,230 7/ 1963 Miller ..260/473 COMPOUNDS 3,078,256 2/1963 Wittig et a1 ..260/606.5 F [72] Inventors: Donald Leroy Roberts; William 2,945,069 7/ 1960 Stern ..260/606.5 F Yates Rice Jr both of winstom 2,912,467 11/1959 Gerecke et a1 ..260/469 Salem N 2,914,522 11/1959 Ramirez ..260/469 1,123,572 1/1915 Neumann et a1 ..260/469 [73] Assignee: R. J. Reynolds Tobacco Company,

Winston-Salem, N.C. OTHER PUBLICATIONS [22] Filed: Oct, 24, 1968 Chemistry of Organic Compounds Ca rl G. Noller 3rd Edition 1965 pp. 535- 536. [21] App1.No.: 770,429 Chem. Abstracts, Vol. 64, 1966, Co] 10470 Hormelin.

J1. Am. Chem. Soc. Vol. 79, 1957, pp. 6167; 6171, [52] US. Cl ..260/469, 260/473 R, 260/606.5 P Ramirez- [51] Int. Cl ..C07c 69/76 [58] Field of Search ..260/469, 606.5 P rim y Exa in -L rraine A- W in erger Assistant ExaminerR. S. Weissberg [56] References Cited Attorney-Pendleton, Neuman, Williams & Anderson UNITED STATES PATENTS 57 AC 2,114,866 4/1938 Vaughn ..260/989 Synthesis of phosphorane compounds by reaction f 3 3,275,717 9/1966 Butter ..260/989 triarylphosphiney an whaloester and an amine 3,553,298 1/1971 Hodan ..260/967 3,140,283 7/ 1964 Depoorter et a1 ..260/469 2 Claims, No Drawings tion relates to a method for synthesizing phosphoranes of the formula:

R2\\ R1 R3-P=C/ a. c o o R wherein R represents an alkyl group,

R represents hydrogen or an alkyl group,

R R and R each represents an aryl group or a substituted aryl group.

The substituents represented by R are straight chain and branched chain alkyl groups having up to 18 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, octyl, cetyl, lauryl, and the like. R represents hydrogen or an alkyl group of the class described above with respect to R. R R and R represent aryl groups such as phenyl, lower alkylphenyl, wherein the lower alkyl group is, for example, methyl, ethyl, propyl, isopropyl and the like, lower alkoxyphenyl, such as methoxy, ethoxy, propoxy, isopropoxy and the like and halophenyl such as chlorophenyl. Phenyl is the preferred substituent represented by R R and R Previously, preparation of the above phosphorane compounds in non-aqueous medium required the preparation and isolation of the corresponding phosphonium salt. This salt was then reacted with a strong base such as sodium ethoxide to produce the phosphorane. It has now been found that the above phosphorane compounds can be prepared very conveniently, without isolation of the phosphonium salt or the use of strong base, by reacting together a triarylphosphine, an a-haloester, and a secondary or tertiary amine.

Representative triarylphosphines which can be employed to form the above phosphoranes are triphenyl, tri(p-methylphenyl), tri(p-methoxyphenyl), and tri(pchlorophenyl).

The a-haloesters which are employed have the formula R CHXCO R wherein R and R have the same significance as above and X is bromine or chlorine. Representative esters are methyl chloroacetate, ethyl chloroacetate, ethyl bromoacetate, ethyl abromopropionate, lauryl bromoacetate and methyl achlorostearate.

The third reactant is an amine of the type wherein 5 6 3 a s s 'h 4 9 2 4 s u,

The reaction can be performed at ambient temperatures or above. It is generally complete in a period of 0.5 to 48 hours. Recovery of the phosphorane is achieved by filtration of the amine salt formed followed by removal of the solvent. The phosphorane can be used as is or purified by recrystallization from an appropriate solvent.

The following examples illustrate the synthesis method of this invention.

EXAMPLE I A mixture of 8.4 grams of triphenylphosphine, 4.8 grams of ethyl chloroacetate and 10 milliliters of triethylamine was allowed to stand for two days before being filtered. Concentration and extraction with hot ethyl acetate gave 7.7 grams of carbethoxymethylenetriphenylphosphorane.

EXAMPLE II A mixture of 5.4 grams of ethyl bromoacetate (0.05 mole), 13.1 grams of triphenylphosphine (0.05 mole), 6 milliliters of triethanolamine and 10 milliliters of benzene was allowed to stand after initial warming to dissolve all of the materials. After 24 hours, the precipitated triethanolarnine hydrochloride was filtered and the filtrate concentrated to give 13.7 grams of carbethoxymethylenetriphenylphosphorane. Repeating the above reaction in acetone gave 7.6 grams of carbethoxymethylenetriphenylphosphorane.

EXAMPLE III A solution of 60 grams of methyl chloroacetate (0.5 mole) and 131 grams of tn'phenyiphosphine (0.5 mole) in 100 milliliters of benzene was heated under reflux for 2 hours on a steam bath then transferred to a Waring Blender and diluted with 200 milliliters of benzene. To this mixture was added 60 milliliters of triethylamine and the mixture vigorously agitated for short periods over a 30-minute interval. The precipitate was separated and the filtrate concentrated to give grams of carbomethoxymethylenetriphenylphospho rane. The precipitate was treated with water and an additional 83 grams of phosphorane was obtained; the total yield of phosphorane was 173 grams or percent.

EXAMPLE IV A solution of 28.3 grams of tri(p-chlorophenyl)- A produce the plant abscission hormone, abscisic acid, as

disclosed in US. Pat. No. 3,400,158.

Those modifications and equivalents which fall within the spirit of the invention and the scope of the appended claims are to be considered part of the invention.

We claim:

1. A method for synthesizing a compound of the formula R is hydrogen or an alkyl group of one to l8 car- R -P=C bons, C O O R and X is bromine or chlorine;

reactant (c) is a secondary or tertiary amine of the wherein type R represents an alkyl group, R, represents hydrogen or an alkyl group, R5 R R-,, and R each represents phenyl, lower al- Z kylphenyl, lower alkoxyphenyl, or halophenyl which comprises reacting together reactants (a), and wherein wherein reactant (a) is a triarylphosphine in which the aryl 5 6 caH'h CQHB C2H4OH, s m

substituents are selected from phenyl, lower al- 2)n( 1 kylphenyl, lower alkoxyphenyl, or halophenyl; R? C2H5 Cali? F reactant (b) is an whaloester of the formula RCHX 2. A method In accordance with claim 1 wherein R CO R wherein R is an alkyl group of one to 18 carhydrogen and and R4 are each phenyl bon atoms,

UNITEDY STATES PATENT 0FFICl3 "I a CERTIFICATE OF CORRECTION 3,681,428 Dated August 1, 1972 Patent No.

Inventor(s) Donald Leroy Roberts and William Yates Rice Tr It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 63, "(CH (=2,3,4,5 0r 6)" should be (CH2) (n=2,3,4,5 or 6) line 64, "C4H9C2H4OH," should be c 11 C2H4OH,

Column 4, line 14, "(CH (=2,3,4,5 ors6)" should be (CH (n=2,3,4,5 or 6) Signed and sealed this 2nd day of January 1973.v

(SEAL) Attest:

EDWARQMPLETCHERJR. ROBERT GOTTSCHALK rttesting Officer Commissioner of Patents YORM po'wso (069) USCOMM'DC man-Poo 9 U S. GOVERNNKNY HUNTING OFFICE: "I! 0-!l6-33 

2. A method in accordance with claim 1 wherein R1 is hydrogen and R2, R3, and R4 are each phenyl. 